Multi-principal element low modulus ti-zr based medium entropy alloy and method of making

Abstract

The application discloses a multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy and a preparation method thereof. 100‑ 10x Nb 4x Ta 4x Hf 2x Wherein, 1<=x<=4. The application is based on the synergistic effect between the TiZr alloy and the Hf, Nb and Ta alloys, the alloy molar ratio between the two is controlled, the mixed entropy and the valence electron concentration of the alloy are improved, the beta phase forming ability is enhanced, the elastic modulus of the alloy is reduced, and the ductility of the alloy is improved, so that the application scenarios of the alloy material are expanded.

Description

Technical Field

[0001] This invention relates to the field of alloy materials, and more particularly to a multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy and its preparation method. Background Technology

[0002] With the development of the biomedical and materials science fields, higher requirements have been placed on the non-toxicity, low modulus, and high ductility of metallic materials used in bio-implants. Currently, some drawbacks exist in clinically used bio-implant materials. For example, stainless steel releases nickel ions after wear and corrosion, which can cause adverse reactions such as allergies, inflammation, or cell damage in humans, with an incidence rate of 10-15%. Ti-6Al-4V alloy is currently the main bio-implant material used, and although it has good processing properties, it contains harmful Al elements (neurotoxicity risk) and V elements (cytotoxic LD50 < 50 mg / kg). Long-term wear of cobalt-based alloy implants in the body can cause the dissolution of cobalt and nickel ions; when the release of cobalt ions exceeds 0.1 ppm, it can cause local tissue necrosis. Furthermore, the elastic modulus of traditional titanium alloys such as stainless steel, Ti-6Al-4V alloy, and cobalt-based alloys is 110-210 GPa, significantly higher than the 20-40 GPa of cortical bone, which can easily lead to stress shielding effects.

[0003] Related studies have shown that biocompatible elements such as Ti, Zr, Hf, Nb, Ta, and Mo pose relatively little harm to the human body. Therefore, alloy materials containing only these few excellent biocompatible elements are ideal biomedical materials and have attracted widespread attention from materials scientists, clinicians, and medical device manufacturers. In recent years, the thermodynamic high-entropy effect, kinetic slow diffusion effect, structural lattice distortion effect, and performance cocktail effect of high-entropy alloys have provided new ideas for the design of biomedical materials. With reasonable composition design, high-entropy alloy materials can exhibit the performance requirements of low elastic modulus and high elongation, which is expected to broaden their applications in the biomedical field.

[0004] Chinese Patent Application No. 202410394726.1 discloses a low-modulus, high-ductility Ti-Zr high-entropy alloy, its preparation method, and its applications. The general formula of the high-entropy alloy is (TiZr). x M y (Atomic percentage), where x ranges from 40 to 49, y ranges from 0.66 to 6.66, M is Nb, Ta and Mo elements, and the elastic modulus of the alloy is 83 to 100 GPa; the elastic modulus of this Ti-Zr high-entropy alloy is still relatively high, and the alloy does not take into account the intermediate alloy during smelting, and it needs to be smelted at least 10 times to ensure the uniformity of composition, and the smelting process is complicated.

[0005] Chinese Patent Application No. 201910842006.6 discloses a biomedical Ti-Zr-Hf-Nb-Ta high-entropy alloy, wherein the general formula of the high-entropy alloy is Ti. a Zr b Hf c Nb d Ta e (Atomic percentage), where 5≤a≤40, 5≤a≤40, 5≤a≤40, 5≤a≤40, 5≤a≤40, and a+b+c+d+e=100. Although the elastic modulus of the high-entropy alloy is as low as 54GPa, the elongation of the alloy is less than 6%. In addition, when the contents of Hf, Nb, and Ta are too high, the cost of the alloy will also be high.

[0006] Compared to Ti6Al4V, Ti 50 Zr 50 Binary alloys have a lower elastic modulus; their stable phase at low temperatures is the α phase, with an elastic modulus of 86-114 GPa, but this is still far higher than the 20-40 GPa of human bone. In contrast, Ti... 50 Zr 50 In binary alloys, the elastic modulus of the β phase is lower than that of the α phase, but the β phase is only stable at high temperatures. Therefore, Ti can be used as a reference. 50 Zr 50 Using binary alloys as a model, the β phase of the alloy is expanded by adding biocompatible elements such as Hf, Nb, Ta, and Mo, and the elastic modulus of the alloy is reduced by controlling the mixing entropy and valence electron concentration. It is of great significance to design a Ti-Zr-Nb-Ta-Hf biomedical medium-entropy alloy with excellent performance through the design of alloy element content. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy and its preparation method. Based on the synergistic effect between TiZr alloy and Hf, Nb, and Ta alloys, by controlling the alloy molar ratio between the two, the mixing entropy and valence electron concentration of the alloy are increased, the β-phase formation ability is enhanced, the elastic modulus of the alloy is reduced, and the ductility of the alloy is improved, thereby expanding the application scenarios of the alloy material.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] The first aspect of the present invention provides a multi-principal element low-modulus Ti-Zr-based medium-entropy alloy, the composition of which, by atomic percentage, is (TiZr). 100-10x Nb 4x Ta 4x Hf 2x , where 1≤x≤4.

[0010] Preferably, the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy is (TiZr). 90 Nb4Ta4Hf2、(TiZr) 80 Nb8Ta8Hf4、(TiZr) 70 Nb 12 Ta 12 Hf6、(TiZr) 60 Nb 16 Ta 16 At least one of Hf8.

[0011] Preferably, the multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy has a single-phase body-centered cubic crystal structure, and its microstructure is a single β phase.

[0012] Preferably, the mixed entropy of the multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy is 1R~1.6R, and the valence electron concentration is 4~4.5.

[0013] Preferably, the multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy has an elastic modulus of 65~90 GPa, a yield strength of 350~700 MPa, a tensile strength of 730~1000 MPa, and an elongation of 9.5%~25%.

[0014] This invention uses Ti in an equimolar ratio 50 Zr 50 The binary alloy is a model alloy with a valence electron concentration of 4 for Ti and Zr. The mixing entropy and valence electron concentration of the alloy are adjusted by using Nb, Ta, and Hf elements. The ductility of the medium-entropy alloy can be adjusted by regulating the valence electron concentration. Furthermore, Nb, Ta, and Hf are all β-stabilizing elements, allowing for the design of low-elastic-modulus β-titanium alloys. Higher strength can be achieved through lattice distortion, solving the problem that existing medium-entropy alloys cannot achieve a lower elastic modulus and a balance between strength and toughness.

[0015] The aforementioned multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy exhibits a simple body-centered cubic crystal structure. The medium-entropy alloy is a single β-phase structure, with high entropy and high valence electron concentration synergistically enhancing the β-phase formation ability. The alloy possesses excellent strength-toughness matching properties. This multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy fills the gap in existing Ti... 50 Zr 50 The high elastic modulus of alloys and traditional alloys provides new compositional options for low-modulus implant materials in biomedicine, meeting the urgent need for biocompatible, low-elastic-modulus metallic materials in bioimplants.

[0016] This invention utilizes Ti 50 Zr 50 The addition of Nb, Ta, and Hf elements to the alloy can achieve the following objectives:

[0017] (1) Ti 50 Zr 50 The alloy's mixing entropy is only 0.7R. By adding Nb, Ta, and Hf elements, the alloy's mixing entropy can be increased to between 1R and 1.6R, forming a medium-entropy alloy and avoiding the tendency to form intermetallic compounds.

[0018] (2) Nb, Ta and Hf are all β-stable elements, and the high valence electron concentration can form a single β phase, thereby reducing the elastic modulus and ultimately forming a medium-entropy alloy with excellent toughness and low elastic modulus. Its biocompatibility is far superior to that of Ti-6Al-4V, stainless steel and cobalt-based alloys currently in use. At the same time, the low elastic modulus can reduce the stress shielding effect.

[0019] (3) The composition of the multi-principal element low-modulus Ti-Zr based medium-entropy alloy by atomic percentage is (TiZr) 100- 10x Nb 4x Ta 4x Hf 2x Within a certain atomic percentage range, as the atomic percentage of Nb-Ta-Hf increases, the mixing entropy and valence electron concentration of the alloy increase, leading to a gradual increase in the yield strength and tensile strength, and a gradual decrease in elongation of the medium-entropy alloy. However, if the atomic percentage of Nb-Ta-Hf exceeds a certain range, the toughness of the medium-entropy alloy becomes poor. Furthermore, as the atomic percentage of Nb-Ta-Hf increases, the cost of this alloy will increase significantly. Therefore, a value of x of 1 ≤ x ≤ 4 is more suitable.

[0020] The preparation method of the multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy of the present invention is to prepare the multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy through vacuum melting process and multi-pass hot rolling treatment. The whole process is relatively simple. The above-mentioned multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy can meet the urgent need of biocompatible and low elastic modulus metal materials for bioimplants, and provides a new direction for the preparation of medium-entropy alloy materials for bioimplants.

[0021] A second aspect of the present invention provides a method for preparing a multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in the first aspect of the present invention, comprising the following steps:

[0022] S1. After pretreating the Ti, Zr, Nb, Ta, and Hf metal raw materials, the atomic percentage of the Ti-Zr-based entropy alloy is converted into the mass percentage, and then each metal raw material is weighed.

[0023] S2, the Nb, Ta and Hf metal raw materials are vacuum melted for the first time to obtain NbTaHf intermediate alloy ingot;

[0024] S3, the Ti metal raw material is vacuum melted with the NbTaHf master alloy ingot in three separate steps to obtain the NbTaHfTi master alloy ingot.

[0025] S4, the Zr metal raw material and the NbTaHfTi master alloy ingot are subjected to a fifth vacuum melting process to obtain (TiZr). 100-10x Nb 4x Ta 4x Hf 2x Alloy ingots, where 1 ≤ x ≤ 4;

[0026] S5, (TiZr) 100-10x Nb 4x Ta 4x Hf 2x The alloy ingot underwent a sixth vacuum melting process. After melting, the molten alloy was poured into a water-cooled copper mold and cooled to obtain a homogeneous (TiZr) alloy. 100-10x Nb 4x Ta 4x Hf 2x Alloy ingots;

[0027] S6, take the (TiZr) obtained in step S5. 100-10x Nb 4x Ta 4x Hf 2x After the alloy ingot is cooled, it is processed into an alloy plate, and then the alloy plate is subjected to multiple hot rolling processes at high temperature. After each hot rolling process, it is cooled with water to obtain a multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy.

[0028] Preferably, in step S1, the pretreatment includes acid washing, ultrasonic cleaning with ethanol, and vacuum drying.

[0029] Preferably, in step S1, the Ti, Zr, Nb, Ta, and Hf metal raw materials are all elemental metal particles, the purity of the elemental metal particles is ≥99.5%, and the size of the elemental metal particles is 2~10 mm.

[0030] Preferably, in the vacuum melting process in steps S2 to S5, a magnetic levitation induction melting furnace is used, and the voltage of the magnetic levitation induction melting furnace is controlled to be 360~550V, the current to be 450~480A, the melting time for each melting is 15~20min, the melting vacuum degree is 0.016~0.02Pa, and the argon filling pressure is -0.06~0Pa.

[0031] Preferably, in step S2, the atomic percentage of the NbTaHf master alloy ingot is Nb2Ta2Hf1. Preferably, the specific process of step S3 is as follows:

[0032] The Ti metal raw materials were divided into three batches by mass percentage: 8~15%, 20~25%, and 60~72%;

[0033] The Ti metal raw material with 8-15% is subjected to a second vacuum melting with the NbTaHf master alloy ingot to obtain master alloy ingot A;

[0034] 20-25% Ti metal raw material is subjected to a third vacuum melting with intermediate alloy ingot A to obtain intermediate alloy ingot B;

[0035] The remaining 60-72% of Ti metal raw materials were subjected to a fourth vacuum melting process with intermediate alloy ingot B to obtain NbTaHfTi intermediate alloy ingot.

[0036] This invention rapidly obtains medium-entropy alloy samples with different proportions through vacuum melting, and then screens high-entropy alloy samples based on comprehensive performance thresholds, thereby determining the optimal element ratios and process parameters in the medium-entropy alloy. This significantly shortens the optimization cycle of the high-entropy alloy, resulting in rapid and accurate production of high-performance products. Figure 1 As shown, this invention employs six vacuum melting processes, melting five metal raw materials—Ti, Zr, Nb, Ta, and Hf—in batches. Since Nb (melting point 2468℃), Ta (melting point 2996℃), and Hf (melting point 2227℃) have relatively high and similar melting points, the first vacuum melting process yields an Nb₂Ta₂Hf intermediate alloy ingot. Ti metal raw material has the lowest melting point (Ti melting point 1668℃), and is melted in three stages (divided into three batches by mass percentage: 8-15%, 20-25%, and 60-72%). Then, Zr metal raw material (Zr melting point 1852℃) is melted. Finally, after all metal raw materials have been melted, a final melting process (TiZr) is performed. 100- 10x Nb 4x Ta 4x Hf 2x The alloy ingot process aims to gradually reduce the melting point of the alloy and obtain an alloy ingot with uniform chemical composition.

[0037] Preferably, in step S6:

[0038] The thickness of the alloy plate is 10~30mm;

[0039] During the multi-pass hot rolling process, the hot rolling temperature is 700~900℃, the total hot rolling deformation is 70%~90%, and the reduction in pressure per pass is 1.0~2.0mm.

[0040] The preparation method of this invention has a significant impact on the properties of the final alloy, especially the hot rolling temperature and the deformation conditions during hot rolling, which can significantly affect the mechanical properties of the medium-entropy alloy. In the aforementioned hot rolling process, controlling the hot rolling temperature to 700~900℃ and the total hot rolling deformation to 70%~90% can regulate the grain size and recrystallization behavior of the alloy, thereby affecting its mechanical properties.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1. This invention is based on the synergistic effect between TiZr alloy and Nb, Ta, and Hf components. By controlling the alloy molar ratio between the two components, the thermodynamic parameters and mechanical properties of the medium-entropy alloy are regulated. On the one hand, the biocompatibility of the alloy material is guaranteed and the β phase region is expanded. On the other hand, the elastic modulus of the alloy is effectively reduced and the ductility of the alloy is improved. This makes up for the shortcomings of the comprehensive mechanical properties of existing alloys, provides a new compositional option for bio-implantable metal materials, and meets the urgent need for non-toxic low-modulus alloy materials for biomedical implants.

[0043] 2. This invention uses Ti in an equimolar ratio 50 Zr 50 The binary alloy is a model alloy with a valence electron concentration of 4 for Ti and Zr. The mixing entropy and valence electron concentration of the alloy are adjusted by adding Nb, Ta, and Hf elements. The ductility of the medium-entropy alloy is thus adjusted by adjusting the valence electron concentration of the alloy. In addition, Nb, Ta, and Hf are all β-stabilizing elements, which can be used to design low elastic modulus β titanium alloys and achieve higher strength through lattice distortion.

[0044] 3. This invention prepares a medium-entropy alloy material with low elastic modulus and a single β phase by designing the atomic percentage of the alloy, using multiple vacuum melting processes and multiple hot rolling passes, and controlling the hot rolling temperature and deformation amount. This material has good toughness. Attached Figure Description

[0045] Figure 1 This is a flowchart of the preparation method of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy of the present invention;

[0046] Figure 2 The multi-principal element low-modulus Ti-Zr based medium-entropy alloy (TiZr) prepared in Example 1 of this invention. 90 Microstructure of Nb4Ta4Hf2;

[0047] Figure 3 The multi-principal element low-modulus Ti-Zr based medium-entropy alloy (TiZr) prepared in Example 4 of this invention. 90 Microstructure of Nb4Ta4Hf2;

[0048] Figure 4The multi-principal element low-modulus Ti-Zr based medium-entropy alloy (TiZr) prepared in Example 5 of this invention. 90 Microstructure of Nb4Ta4Hf2. Detailed Implementation

[0049] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way.

[0050] The raw materials used in the following examples and comparative examples are all metal raw materials with a purity of ≥99.95% and a particle size of 2~10mm.

[0051] Example 1

[0052] The composition of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy in this embodiment is (TiZr). 90 Nb4Ta4Hf2, where each element is expressed as an atomic percentage.

[0053] Step 1: Before smelting, the elemental metal raw materials Ti, Zr, Nb, Ta and Hf are cleaned by acid washing, ultrasonic alcohol cleaning and vacuum drying respectively.

[0054] Step 2: Press (TiZr) 90 Convert the atomic percentage of Nb4Ta4Hf2 to the mass percentage, and accurately weigh the cleaned metallic elements Ti, Zr, Nb, Ta and Hf to an accuracy of 0.1 mg.

[0055] Step 3: Place the Nb, Ta and Hf metal raw materials in a magnetic levitation induction melting furnace for the first vacuum melting. After the melting is completed, pour the alloy melt into a copper mold to cool and obtain the Nb4Ta4Hf2 intermediate alloy ingot.

[0056] Step 4: Place the Nb4Ta4Hf2 intermediate alloy ingot and 10% Ti metal raw material in a magnetic levitation induction melting furnace for a second vacuum melting. After melting, pour the alloy melt into a copper mold to cool, obtaining Ti. 5.5 Nb4Ta4Hf2 master alloy ingot (i.e., master alloy ingot A).

[0057] Step 5: Place Ti 5.5 The Nb4Ta4Hf2 master alloy ingot and 20% Ti metal raw material were placed in a magnetic levitation induction melting furnace for a third vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling to obtain Ti. 16.5 Nb4Ta4Hf2 intermediate alloy ingot (i.e., intermediate alloy ingot B).

[0058] Step 6: Place Ti16.5 The Nb4Ta4Hf2 intermediate alloy ingot and the remaining 70% of the Ti metal raw material were placed in a magnetic levitation induction melting furnace for a fourth vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling to obtain Ti. 45 Nb4Ta4Hf2 master alloy ingot (i.e. NbTaHfTi master alloy ingot).

[0059] Step 7: Place Ti 45 The Nb4Ta4Hf2 intermediate alloy ingot and all Zr metal raw materials were placed in a magnetic levitation induction melting furnace for the fifth vacuum melting. After the melting was completed, the alloy melt was poured into a copper mold and cooled to obtain (TiZr). 90 Nb4Ta4Hf2 alloy ingots.

[0060] Step 8: (TiZr) 90 The Nb4Ta4Hf2 alloy ingot was placed in a magnetic levitation induction melting furnace for the sixth vacuum melting. After the melting was completed, the alloy melt was poured into a copper mold for cooling, resulting in a homogeneous (TiZr) alloy. 90 Nb4Ta4Hf2 alloy ingots.

[0061] During the six vacuum melting processes mentioned above, the voltage of the magnetic levitation induction melting furnace was controlled at 360V, the current at 450A, the melting time for each process was 20 minutes, the melting vacuum degree was 0.016Pa, and the argon filling pressure was -0.06Pa.

[0062] Step 9: Using wire cutting, the alloy ingot obtained in step 8 is processed into 10mm thick round sheets; then, it is hot rolled at 700℃ using a multi-pass hot rolling process, with a total deformation of 80% and a reduction of 1.0mm per pass. After hot rolling, it is cooled with water to obtain (TiZr). 90 Nb4Ta4Hf2 medium entropy alloy.

[0063] This embodiment (TiZr) 90 The Nb4Ta4Hf2 medium-entropy alloy has a single-phase body-centered cubic crystal structure; its microstructure is described in [reference needed]. Figure 2 As shown, the microstructure is a single β phase.

[0064] This embodiment (TiZr) 90 The arithmetic mean of the grain size of the Nb4Ta4Hf2 medium-entropy alloy is 56 µm, and the area-weighted average of the grain size is 98 µm. The aforementioned medium-entropy alloy exhibits a grain size distribution of 5 × 10⁻⁶ µm at room temperature. -4 The strain rate was tested at / s, and the results showed that the elastic modulus was 73 GPa, the yield strength was 391 MPa, the tensile strength was 800 MPa, and the elongation was 21%. (TiZr) 90The mixed entropy of the Nb4Ta4Hf2 medium-entropy alloy is 1.05R, and the valence electron concentration is 4.08.

[0065] Example 2

[0066] The composition of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy in this embodiment is (TiZr). 70 Nb 12 Ta 12 Hf6, where each element is expressed as an atomic percentage.

[0067] Step 1: Before smelting, the elemental metal raw materials Ti, Zr, Nb, Ta and Hf are cleaned by acid washing, ultrasonic alcohol cleaning and vacuum drying respectively.

[0068] Step 2: Press (TiZr) 70 Nb 12 Ta 12 Convert the atomic percentage of Hf6 to the mass percentage, and accurately weigh the cleaned metallic elements Ti, Zr, Nb, Ta and Hf to an accuracy of 0.1 mg.

[0069] Step 3: Place the Nb, Ta, and Hf metal raw materials in a magnetic levitation induction melting furnace for the first vacuum melting. After melting, pour the alloy melt into a copper mold to cool, and obtain Nb. 12 Ta 12 Hf6 intermediate alloy ingot.

[0070] Step 4: Add Nb 12 Ta 12 Hf6 master alloy ingot and 10% Ti metal raw material are placed in a magnetic levitation induction melting furnace for a second vacuum melting. After melting, the alloy melt is poured into a copper mold and cooled to obtain Ti. 3.5 Nb 12 Ta 12 Hf6 intermediate alloy ingot.

[0071] Step 5: Place Ti 3.5 Nb 12 Ta 12 Hf6 master alloy ingot and 20% Ti metal raw material were placed in a magnetic levitation induction melting furnace for a third vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling to obtain Ti. 10.5 Nb 12 Ta 12 Hf6 intermediate alloy ingot.

[0072] Step 6: Place Ti 10.5 Nb 12 Ta 12The Hf6 intermediate alloy ingot and the remaining 70% of the Ti metal raw material were placed in a magnetic levitation induction melting furnace for a fourth vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling to obtain Ti. 35 Nb 12 Ta 12 Hf6 intermediate alloy ingot.

[0073] Step 7: Place Ti 35 Nb 12 Ta 12 The Hf6 intermediate alloy ingot and all Zr metal raw materials were placed in a magnetic levitation induction melting furnace for the fifth vacuum melting. After the melting was completed, the alloy melt was poured into a copper mold and cooled to obtain (TiZr). 70 Nb 12 Ta 12 Hf6 alloy ingots.

[0074] Step 8: (TiZr) 70 Nb 12 Ta 12 Hf6 alloy ingots were placed in a magnetic levitation induction melting furnace for a sixth vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling, resulting in a homogeneous (TiZr) alloy. 70 Nb 12 Ta 12 Hf6 alloy ingots.

[0075] During the six vacuum melting processes mentioned above, the voltage of the magnetic levitation induction melting furnace was controlled at 550V, the current at 480A, the melting time for each process was 15min, the melting vacuum degree was 0.02Pa, and the argon gas pressure was 0Pa.

[0076] Step 9: Using wire cutting, the alloy ingot obtained in step 8 is processed into 10mm thick round sheets; then, it is hot rolled at 700℃ using a multi-pass hot rolling process, with a total deformation of 80% and a reduction of 1.0mm per pass. After hot rolling, it is cooled with water to obtain (TiZr). 70 Nb 12 Ta 12 Hf6 medium entropy alloy.

[0077] The obtained (TiZr) 70 Nb 12 Ta 12 Hf6 medium-entropy alloys have an entropy of 5 × 10⁻⁶ at room temperature -4 The strain rate was tested at / s, and the results showed that the elastic modulus was 80 GPa, the yield strength was 554 MPa, the tensile strength was 901 MPa, and the elongation was 14%. (TiZr) 90The mixed entropy of the Nb4Ta4Hf2 medium-entropy alloy is 1.41R, and the valence electron concentration is 4.24.

[0078] Example 3

[0079] The composition of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy in this embodiment is (TiZr). 60 Nb 16 Ta 16 Hf8, where each element is represented by its atomic percentage.

[0080] Step 1: Before smelting, the elemental metal raw materials Ti, Zr, Nb, Ta and Hf are cleaned by acid washing, ultrasonic alcohol cleaning and vacuum drying respectively.

[0081] Step 2: Press (TiZr) 60 Nb 16 Ta 16 Convert the atomic percentage of Hf8 to the mass percentage, and accurately weigh the cleaned metallic elements Ti, Zr, Nb, Ta and Hf to an accuracy of 0.1 mg.

[0082] Step 3: Place the Nb, Ta, and Hf metal raw materials in a magnetic levitation induction melting furnace for the first vacuum melting. After melting, pour the alloy melt into a copper mold to cool, and obtain Nb. 16 Ta 16 Hf8 intermediate alloy ingot.

[0083] Step 4: Add Nb 16 Ta 16 Hf8 intermediate alloy ingot and 10% Ti metal raw material were placed in a magnetic levitation induction melting furnace for a second vacuum melting. After melting, the alloy melt was poured into a copper mold and cooled to obtain Ti3Nb. 16 Ta 16 Hf8 intermediate alloy ingot.

[0084] Step 5: Apply Ti3Nb 16 Ta 16 Hf8 intermediate alloy ingot and 20% Ti metal raw material were placed in a magnetic levitation induction melting furnace for a third vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling to obtain Ti9Nb. 16 Ta 16 Hf8 intermediate alloy ingot.

[0085] Step 6: Apply Ti9Nb 16 Ta 16The Hf8 intermediate alloy ingot and the remaining 70% of the Ti metal raw material were placed in a magnetic levitation induction melting furnace for a fourth vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling to obtain Ti. 30 Nb 16 Ta 16 Hf8 intermediate alloy ingot.

[0086] Step 7: Place Ti 30 Nb 16 Ta 16 The Hf8 intermediate alloy ingot and all Zr metal raw materials were placed in a magnetic levitation induction melting furnace for the fifth vacuum melting. After the melting was completed, the alloy melt was poured into a copper mold and cooled to obtain (TiZr). 60 Nb 16 Ta 16 Hf8 alloy ingots.

[0087] Step 8: (TiZr) 60 Nb 16 Ta 16 Hf8 alloy ingots were placed in a magnetic levitation induction melting furnace for a sixth vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling, resulting in a homogeneous (TiZr) alloy. 60 Nb 16 Ta 16 Hf8 medium-entropy alloy ingot.

[0088] During the six vacuum melting processes mentioned above, the voltage of the magnetic levitation induction melting furnace was controlled at 450V, the current at 460A, the melting time for each process was 18min, the melting vacuum degree was 0.018Pa, and the argon filling pressure was -0.03Pa.

[0089] Step 9: Using wire cutting, the medium-entropy alloy ingot obtained in step 8 is processed into 10mm thick circular sheets; then, it is hot rolled at 700℃ using a multi-pass hot rolling process, with a total deformation of 80% and a reduction of 1.0mm per pass. After hot rolling, it is cooled with water to obtain (TiZr). 60 Nb 16 Ta 16 Hf8 medium entropy alloy.

[0090] The obtained (TiZr) 60 Nb 16 Ta 16 Hf8 medium-entropy alloys have a growth rate of 5 × 10⁻⁶ at room temperature. -4 The strain rate was tested at / s, and the results showed that the elastic modulus was 89 GPa, the yield strength was 672 MPa, the tensile strength was 967 MPa, and the elongation was 10%. (TiZr) 60 Nb16 Ta 16 The mixed entropy of the Hf8 medium-entropy alloy is 1.51R, and the valence electron concentration is 4.32.

[0091] Example 4

[0092] The composition of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy in this embodiment is (TiZr). 90 Nb4Ta4Hf2, where each element is expressed as an atomic percentage.

[0093] This embodiment uses the preparation method of Example 1, with the only difference being that the hot rolling temperature in the ninth step is 800℃ and the total rolling deformation is 80%.

[0094] The (TiZr) obtained in this embodiment 90 The Nb4Ta4Hf2 medium-entropy alloy has an arithmetic mean grain size of 36 µm and an area-weighted average grain size of 138 µm. The aforementioned medium-entropy alloy exhibits a grain size distribution of 5 × 10⁻⁶ at room temperature. -4 The strain rate was tested at / s, and the results showed that the elastic modulus was 74 GPa, the yield strength was 464 MPa, the tensile strength was 735 MPa, and the elongation was 9.8%. (TiZr) 90 The mixed entropy of the Nb4Ta4Hf2 medium-entropy alloy is 1.05R, and the valence electron concentration is 4.08.

[0095] Example 5

[0096] The composition of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy in this embodiment is (TiZr). 90 Nb4Ta4Hf2, where each element is expressed as an atomic percentage.

[0097] This embodiment uses the preparation method of Example 1, with the only difference being that the hot rolling temperature in the ninth step is 900℃ and the total rolling deformation is 80%.

[0098] The (TiZr) obtained in this embodiment 90 The Nb4Ta4Hf2 medium-entropy alloy has an arithmetic mean grain size of 130 µm and an area-weighted average grain size of 203 µm. The aforementioned medium-entropy alloy exhibits a grain size distribution of 5 × 10⁻⁶ at room temperature. -4 The strain rate was tested at / s, and the results showed that the elastic modulus was 71 GPa, the yield strength was 378 MPa, the tensile strength was 788 MPa, and the elongation was 22%. (TiZr) 90 The mixed entropy of the Nb4Ta4Hf2 medium-entropy alloy is 1.05R, and the valence electron concentration is 4.08.

[0099] Example 6

[0100] The composition of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy in this embodiment is (TiZr). 90 Nb4Ta4Hf2, where each element is expressed as an atomic percentage.

[0101] This embodiment uses the preparation method of Example 1, with the only difference being that the total deformation of the rolling in the ninth step is 70%.

[0102] The obtained (TiZr) 90 Nb4Ta4Hf2 medium-entropy alloys exhibit a growth rate of 5 × 10⁻⁶ at room temperature. -4 The strain rate was tested at / s, and the results showed that the elastic modulus was 69 GPa, the yield strength was 363 MPa, the tensile strength was 763 MPa, and the elongation was 25%. (TiZr) 90 The mixed entropy of the Nb4Ta4Hf2 medium-entropy alloy is 1.05R, and the valence electron concentration is 4.08.

[0103] Example 7

[0104] The composition of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy in this embodiment is (TiZr). 90 Nb4Ta4Hf2, where each element is expressed as an atomic percentage.

[0105] This embodiment uses the preparation method of Example 1, with the only difference being that the total deformation of the rolling in the ninth step is 90%.

[0106] The obtained (TiZr) 90 Nb4Ta4Hf2 medium-entropy alloys exhibit a growth rate of 5 × 10⁻⁶ at room temperature. -4 The strain rate was tested at / s, and the results showed that the elastic modulus was 79 GPa, the yield strength was 421 MPa, the tensile strength was 831 MPa, and the elongation was 18%. (TiZr) 90 The mixed entropy of the Nb4Ta4Hf2 medium-entropy alloy is 1.05R, and the valence electron concentration is 4.08.

[0107] Example 8

[0108] The composition of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy in this embodiment is (TiZr). 90 Nb4Ta4Hf2, where each element is expressed as an atomic percentage.

[0109] This embodiment uses the preparation method of Example 1, with the only difference being that the proportions of Ti metal raw materials in steps four, five, and six are 8%, 20%, and 72%, respectively.

[0110] The obtained (TiZr) 90 Nb4Ta4Hf2 medium-entropy alloys exhibit a growth rate of 5 × 10⁻⁶ at room temperature.-4 The strain rate was tested at / s, and the results showed that the elastic modulus was 72 GPa, the yield strength was 380 MPa, the tensile strength was 793 MPa, and the elongation was 20%. (TiZr) 90 The mixed entropy of the Nb4Ta4Hf2 medium-entropy alloy is 1.05R, and the valence electron concentration is 4.08.

[0111] Example 9

[0112] The composition of the multi-principal element low-modulus Ti-Zr-based medium-entropy alloy in this embodiment is (TiZr). 90 Nb4Ta4Hf2, where each element is expressed as an atomic percentage.

[0113] This embodiment uses the preparation method of Example 1, with the only difference being that the proportions of Ti metal raw materials in steps four, five, and six are 15%, 25%, and 60%, respectively.

[0114] The obtained (TiZr) 90 Nb4Ta4Hf2 medium-entropy alloys exhibit a growth rate of 5 × 10⁻⁶ at room temperature. -4 The strain rate was tested at / s, and the results showed that the elastic modulus was 73 GPa, the yield strength was 396 MPa, the tensile strength was 812 MPa, and the elongation was 23%. (TiZr) 90 The mixed entropy of the Nb4Ta4Hf2 medium-entropy alloy is 1.05R, and the valence electron concentration is 4.08.

[0115] Comparative Example 1

[0116] The medium-entropy alloy composition in this comparative example is (TiZr). 50 Nb 20 Ta 20 Hf 10 In this context, each element is represented by its atomic percentage.

[0117] Step 1: Before smelting, the elemental metal raw materials Ti, Zr, Nb, Ta and Hf are cleaned by acid washing, ultrasonic alcohol cleaning and vacuum drying respectively.

[0118] Step 2: Press (TiZr) 50 Nb 20 Ta 20 Hf 10 Convert the atomic percentages to mass percentages and accurately weigh the cleaned elemental metals Ti, Zr, Nb, Ta, and Hf to an accuracy of 0.1 mg.

[0119] Step 3: Place the Nb, Ta, and Hf metal raw materials in a magnetic levitation induction melting furnace for the first vacuum melting. After melting, pour the alloy melt into a copper mold to cool, and obtain Nb. 20 Ta 20 Hf 10 Intermediate alloy ingot.

[0120] Step 4: Add Nb 20 Ta 20 Hf 10 The intermediate alloy ingot and 10% Ti metal raw material were placed in a magnetic levitation induction melting furnace for a second vacuum melting. After the melting was completed, the alloy melt was poured into a copper mold and cooled to obtain Ti5Nb. 20 Ta 20 Hf 10 Intermediate alloy ingot.

[0121] Step 5: Apply Ti5Nb 20 Ta 20 Hf 10 The intermediate alloy ingot and 20% Ti metal raw material were placed in a magnetic levitation induction melting furnace for a third vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling to obtain Ti. 15 Nb 20 Ta 20 Hf 10 Intermediate alloy ingot.

[0122] Step 6: Place Ti 15 Nb 20 Ta 20 Hf 10 The intermediate alloy ingot and the remaining 70% of the Ti metal raw material were placed in a magnetic levitation induction melting furnace for a fourth vacuum melting process. After melting, the alloy melt was poured into a copper mold for cooling to obtain Ti. 25 Nb 20 Ta 20 Hf 10 Intermediate alloy ingot.

[0123] Step 7: Place Ti 25 Nb 20 Ta 20 Hf 10 The intermediate alloy ingot and all Zr metal raw materials were placed in a magnetic levitation induction melting furnace for the fifth vacuum melting. After the melting was completed, the alloy melt was poured into a copper mold and cooled to obtain (TiZr). 50 Nb 20 Ta 20 Hf10 ingot.

[0124] Step 8: (TiZr) 50 Nb20 Ta 20 Hf 10 The ingot was placed in a magnetic levitation induction melting furnace for a sixth vacuum melting process. After the melting was completed, the alloy melt was poured into a copper mold for cooling, resulting in a homogeneous (TiZr) alloy. 50 Nb 20 Ta 20 Hf 10 Medium-entropy alloy ingots.

[0125] Step 9: Using wire cutting, process the medium-entropy alloy ingot obtained in step 8 into a 10mm thick round sheet; then hot roll it at 700℃ using a multi-pass hot rolling process, with a total deformation of 80% and a pressing amount of 1.0mm per pass. After hot rolling, cool it with water.

[0126] The obtained (TiZr) 50 Nb 20 Ta 20 Hf 10 Medium entropy alloys at room temperature have an entropy of 5 × 10⁻⁶. -4 The strain rate was tested at / s, and the results showed that the elastic modulus was 95 GPa, the yield strength was 702 MPa, the tensile strength was 1034 MPa, and the elongation was 9%. (TiZr) 50 Nb 20 Ta 20 Hf 10 The mixed entropy of the medium-entropy alloy is 1.57R, and the valence electron concentration is 4.4.

[0127] Comparative Example 2

[0128] The alloy composition of this comparative example is Ti. 50 Zr 50 In this context, each element is represented by its atomic percentage.

[0129] Step 1: Before smelting, the Ti and Zr metal raw materials are cleaned by acid washing, ultrasonic alcohol cleaning and vacuum drying respectively.

[0130] Step 2: Press Ti 50 Zr 50 Convert the atomic percentages to mass and accurately weigh the cleaned Ti and Zr metals to an accuracy of 0.1 mg.

[0131] Step 3: Place all metal raw materials in a magnetic levitation induction melting furnace for vacuum melting. Control the voltage at 550V and the current at 450A, and perform three melting cycles, each lasting 20 minutes. After melting, pour the molten alloy into a copper mold, cool, and obtain Ti. 50 Zr 50 Alloy ingots.

[0132] Step 4: Using wire cutting, the alloy ingot obtained in step 8 is processed into a 10mm thick round sheet; then it is hot rolled at 700℃, using multiple hot rolling processes, with a total deformation of 80% and a pressing amount of 0.8mm per pass. During each cold rolling process, the sample temperature increases, and water is used for cooling.

[0133] The obtained Ti 50 Zr 50 The alloy at room temperature has a strength of 5 × 10⁻⁶ -4 The strain rate was tested at / s, and the results showed that the yield strength was 915 MPa, the tensile strength was 1063 MPa, and the elongation was 6%.

[0134] Figure 2 (TiZr) prepared in Example 1 90 Microstructure of Nb4Ta4Hf2 medium-entropy alloy Figure 3 (TiZr) prepared in Example 4 90 Microstructure of Nb4Ta4Hf2 medium-entropy alloy Figure 4 (TiZr) prepared in Example 5 90 Microstructure of Nb4Ta4Hf2 medium-entropy alloy. As shown in the figure, (TiZr) 90 The microstructure of the Nb4Ta4Hf2 medium-entropy alloy is a single β phase; the arithmetic mean of the grain size of the alloy is 30~130μm, and the area-weighted average of the grain size is 90~210μm; in addition, the amount of hot rolling deformation also has a significant impact on the grain size, thus exhibiting different mechanical property parameters.

[0135] Table 1

[0136]

[0137] Table 2

[0138]

[0139] As can be seen from Examples 1-3 and Comparative Example 1, different medium-entropy alloy compositions result in different mixing entropy and valence electron concentrations, leading to variations in the alloy's elastic modulus, yield strength, tensile strength, and elongation. With increasing x, the mixing entropy, valence electron concentration, elastic modulus, yield strength, and tensile strength all show an increasing trend, while the elongation shows a decreasing trend. Furthermore, with increasing x, the price of the alloy's raw materials will continue to increase. Although the composition of Comparative Example 1 is consistent with the present invention, its atomic percentages are outside the scope of the present invention, resulting in a higher elastic modulus and lower elongation, which does not meet the requirements of the alloy of the present invention. Therefore, to achieve a lower elastic modulus and excellent strength-toughness matching performance in the alloy, and to control costs during alloy design, the atomic percentages of the alloy need to be controlled within a suitable range.

[0140] As can be seen from Examples 1, 4, and 5, the elastic modulus, yield strength, tensile strength, and elongation of the alloy fluctuate within a reasonable range as the hot rolling temperature changes. As shown in Table 2, the elastic modulus of the alloys prepared in Examples 1, 4, and 5 is ≤74 GPa, and the elongation is ≥9.80%, exhibiting both low elastic modulus and good elongation.

[0141] As can be seen from Examples 1, 6, and 7, as the total deformation of hot rolling increases, the elastic modulus, yield strength, and tensile strength of the alloy increase, while the elongation decreases. As shown in Table 2, the elastic modulus (<80 GPa) of the alloys in Examples 1, 6, and 7 is much lower than that of the alloy in the comparative example, and the elongation (≥18%) of the alloys in Examples 1, 6, and 7 is much higher than that of the comparative example.

[0142] As can be seen from Examples 1, 8, and 9, melting the Ti metal raw material three times during the smelting process gradually lowers the melting point of the alloy, resulting in an alloy ingot with uniform chemical composition, which gives the alloy a lower elastic modulus and excellent elongation.

[0143] As shown in Table 2, the multi-principal-element low-modulus Ti-Zr-based medium-entropy alloys prepared in Examples 1-9 have an elastic modulus of 69-90 GPa, a yield strength of 363-672 MPa, a tensile strength of 735-967 MPa, an elongation of 9.8%-25%, a mixing entropy of 1.05-1.51R, and a valence electron concentration of 4.08-4.32. Compared with Comparative Examples 1 and 2, the medium-entropy alloys prepared in the examples of this invention have a lower elastic modulus and a good elongation, achieving a balance between a lower elastic modulus and excellent strength-toughness ratio.

[0144] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A multi-principal element low-modulus Ti-Zr-based medium-entropy alloy, characterized in that, Its composition, by atomic percentage, is (TiZr). 100-10x Nb 4x Ta 4x Hf 2x Where 1 ≤ x ≤ 4; The elastic modulus of the multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy is 65~90 GPa, and the elongation is 9.5%~25%.

2. The multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 1, characterized in that, The multi-principal element low-modulus Ti-Zr based medium-entropy alloy is (TiZr). 90 Nb4Ta4Hf2、(TiZr) 80 Nb8Ta8Hf4、(TiZr) 70 Nb 12 Ta 12 Hf6、(TiZr) 60 Nb 16 Ta 16 At least one of Hf8.

3. The multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 1, characterized in that, The multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy has a single-phase body-centered cubic crystal structure, and its microstructure is a single β phase.

4. The multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 1, characterized in that, The mixed entropy of the multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy is 1R~1.6R, and the valence electron concentration is 4~4.

5.

5. The multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 1, characterized in that, The yield strength of the multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy is 350~700 MPa, and the tensile strength is 730~1000 MPa.

6. A method for preparing a multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. After pretreatment of Ti, Zr, Nb, Ta, and Hf metal raw materials, weigh each metal raw material according to the atomic percentage of the Ti-Zr-based entropy alloy. S2, the Nb, Ta and Hf metal raw materials are vacuum melted for the first time to obtain NbTaHf intermediate alloy ingot; S3, the Ti metal raw material is vacuum melted with the NbTaHf master alloy ingot in three separate steps to obtain the NbTaHfTi master alloy ingot. S4, the Zr metal raw material and the NbTaHfTi master alloy ingot are subjected to a fifth vacuum melting process to obtain (TiZr). 100- 10x Nb 4x Ta 4x Hf 2x Alloy ingots, where 1 ≤ x ≤ 4; S5, (TiZr) 100-10x Nb 4x Ta 4x Hf 2x The alloy ingot underwent a sixth vacuum melting process. After melting, the molten alloy was poured into a water-cooled copper mold and cooled to obtain a homogeneous (TiZr) alloy. 100-10x Nb 4x Ta 4x Hf 2x Alloy ingots; S6, take the (TiZr) obtained in step S5. 100-10x Nb 4x Ta 4x Hf 2x After the alloy ingot is cooled, it is processed into an alloy plate, and then the alloy plate is subjected to multiple hot rolling processes at high temperature. After each hot rolling process, it is cooled with water to obtain a multi-principal-element low-modulus Ti-Zr-based medium-entropy alloy.

7. The method for preparing a multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 6, characterized in that, In step S1, the pretreatment includes acid washing, ultrasonic cleaning with ethanol, and vacuum drying.

8. The method for preparing a multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 6, characterized in that, In step S1, the Ti, Zr, Nb, Ta, and Hf metal raw materials are all made of elemental metal particles, the purity of the elemental metal particles is ≥99.5%, and the size of the elemental metal particles is 2~10 mm.

9. The method for preparing a multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 6, characterized in that, In the vacuum melting process in steps S2 to S5, a magnetic levitation induction melting furnace is used. The voltage of the magnetic levitation induction melting furnace is controlled at 360~550V, the current is 450~480A, the melting time is 15~20min, the melting vacuum degree is 0.016~0.02Pa, and the argon gas pressure is -0.06~0Pa.

10. The method for preparing a multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 6, characterized in that, In step S2, the atomic percentage of the NbTaHf master alloy ingot is Nb2Ta2Hf1.

11. The method for preparing a multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 6, characterized in that, The specific process of step S3 is as follows: The Ti metal raw materials were divided into three batches by mass percentage: 8~15%, 20~25%, and 60~72%; The Ti metal raw material with 8-15% is subjected to a second vacuum melting with the NbTaHf master alloy ingot to obtain master alloy ingot A; 20-25% Ti metal raw material is subjected to a third vacuum melting with intermediate alloy ingot A to obtain intermediate alloy ingot B; The remaining 60-72% of Ti metal raw materials were subjected to a fourth vacuum melting process with intermediate alloy ingot B to obtain NbTaHfTi intermediate alloy ingot.

12. The method for preparing a multi-principal element low-modulus Ti-Zr-based medium-entropy alloy as described in claim 6, characterized in that, In step S6: The thickness of the alloy plate is 10~30mm; During the multi-pass hot rolling process, the hot rolling temperature is 700~900℃, the total hot rolling deformation is 70%~90%, and the reduction in pressure per pass is 1.0~2.0mm.

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